The present invention relates to an electrophotographic copier of the type having a movable member carrying a photoconductive layer, a charging station for charging the layer, an illuminating station for photographically exposing the layer, a developing station provided with a magnetic brush and arranged to supply a magnetic single component toner to the brush for developing the image formed on the layer, a transfer station for transferring the developed image to a record material sheet, and a cleaning station for cleaning the layer, the stations being disposed in succession along the path of movement of the movable member for bringing each portion of the layer into operative association with each station in succession, in combination with a cassette containing a supply of such toner.
Electrophotographic copiers, referred to hereinafter as photocopiers, customarily use a powdered toner to develop a latent electrostatic image created on a photoconductive layer on a belt or drum. Powder particles are dusted or brushed over the latent image and these particles are selectively attracted by electrostatically charged zones on the photoconductive layer to form a visible pattern, or image, of powder particles corresponding to the latent image. Since toner powder is consumed in the process, it is necessary to periodically replenish the photocopier with new toner. However, the conventional, commercially available toner powders are extremely difficult to handle. These toners blacken everything with which they come into contact. Moreover, it is difficult to completely empty a toner container.
Disposable commercially available toner containers are generally opened by the user who then empties their contents into a toner discharge device in the photocopier. Manual emptying of the toner container into the toner discharge device without blackening oneself or one's clothing can be performed only with difficulty and is often impossible. If the user uses a toner cassette or cartridge, he is left with a lid or sealing element which has already been soiled with toner. Additionally, it often happens very easily that part of the toner powder from this cover or sealing element inadvertently comes into contact with, and soils, the user's hands or clothing.
German Offenlegungsschrift No. 2,705,646 discloses a photocopier in which the toner is supplied in a closed cassette to a reservoir container in the developing apparatus. This cassette is disposable and is designed so that it cannot be reused once its content of developing powder has been used up. Reuse of the cassette after emptying is impossible. Moreover, in copiers employing a single component toner as the developing powder, the residual toner removed from the photoconductive layer by the cleaning apparatus cannot be returned to the reservoir container of the developing device.